Immersion lithography typically involves exposing a coated resist to a pattern through a de-ionized water (DIW) filled in the space between a project lens and the resist layer for higher resolution. Current immersion lithography processes may include various processing steps such as resist coating, pre-baking, immersion exposing, post-exposure baking, developing, and hard baking. However, the current immersion lithography processes experience various contaminations and particle defects from wafers and components of the lithography system, resulting in pattern defects, pattern distortion, and pattern loss. It is also a challenge to effectively and efficiently monitor particles during an immersion lithography process.